AgI-Ag2O-V2O5 glasses as ion-to-electron transducers for the construction of all-solid-state microelectrodes

A method for the fabrication of ion-selective all-solid-state microelectrodes is presented. The ion-to-electron transduction process takes place into the transducer material. In this approach, AgI-Ag₂O-V₂O₅ glasses, which exhibit ionic and electrical conductivity are applied as ion-to-electron transducers of polymeric membrane microelectrodes. All-solid-state electrodes based on potassium-sensitive poly(vinyl chloride) membranes, deposited directly on the surface of glass composites, exhibited theoretical responses. Their selectivity and durability were comparable to planar microelectrodes containing an internal electrolyte immobilized in the intermediate hydrogel layer. The only disadvantage of the proposed structures was their limited reproducibility. Moreover, it was found that the unmodified AgI-Ag₂O-V₂O₅ glasses can be applied as ion-sensitive membrane of solid-state microelectrodes for the determination of Ag⁺ and I⁻ ions.     

Inverse problems for multi-valued quasi variational inequalities and noncoercive variational inequalities with noisy data

ABSTRACT

We study the inverse problem of identifying a variable parameter in variational and quasi-variational inequalities. We consider a quasi-variational inequality involving a multi-valued monotone map and give a new existence result. We then formulate the inverse problem as an optimization problem and prove its solvability. We also conduct a thorough study of the inverse problem of parameter identification in noncoercive variational inequalities which appear commonly in applied models. We study the inverse problem by posing optimization problems using the output least-squares and the modified output least-squares. Using regularization, penalization, and smoothing, we obtain a single-valued parameter-to-selection map and study its differentiability. We consider optimization problems using the output least-squares and the modified output least-squares for the regularized, penalized and smoothened variational inequality. We give existence results, convergence analysis, and optimality conditions. We provide applications and numerical examples to justify the proposed framework.     

Studies of intrawall porosity in the hexagonally ordered mesostructures of SBA-15 by small angle X-ray scattering and nitrogen adsorption

Ordered mesoporous silicas (OMSs) such as SBA-15 (p6mm symmetry group) synthesized in the presence of block copolymers containing poly(ethylene oxide) blocks possess irregular complementary pores in the walls of ordered mesopores. The X-ray scattering caused by this complementary porosity contributes to the background of the SAXS patterns. This work shows the possibility of using the SAXS data for the study of intrawall channels interconnecting ordered cylinders in SBA-15. The proposed SAXS analysis was tested by using a series of SBA-15 samples obtained at different temperatures of hydrothermal treatment (from 60 to 180 °C). The structural modelling of the SAXS patterns recorded for a series of SBA-15 samples was performed by using the continuous density function (CDF) technique in combination with the derivative difference minimization (DDM) method of full-profile refinement. This method is well suited for extraction of the background curves from the SAXS patterns. The resulting smooth background curves were analyzed by the well-known method in the SAXS theory used for evaluation of heterogeneity distributions, which in this case characterize the intrawall complementary porosity. A relatively good agreement has been observed between the data obtained by SAXS and nitrogen adsorption analysis. The SAXS analysis is sufficiently sensitive for examination of heterogeneous microporosity in SBA-15 materials. The average diameter of intrawall pores for the SBA-15 sample obtained at 60 °C was only about 1.4 nm. However, this diameter increased with the increasing temperature of hydrothermal treatment; namely, it was 1.5, 1.8, 2.6, 2.6, 3.5 and 5.2 nm for the SBA-15 samples hydrothermally treated at 80, 100, 120, 140, 160 and 180 °C, respectively.     

S-adenosylhomocysteine analogues with the carbon-5' and sulfur atoms replaced by a vinyl unit

Cross-metathesis of suitably protected 5'-deoxy-5'-methyleneadenosines with racemic and chiral N-Boc-protected six-carbon amino acids bearing a terminal double bond in the presence of the Hoveyda-Grubbs catalyst gave adenosylhomocysteine analogues with the C5'-C6' double bond. Bromination with pyridinium tribromide and dehydrobromination with DBU followed by standard deprotections yielded the 5'-(bromo)vinyl analogue. [structure: see text]     

Constructing tilted algebras from cluster-tilted algebras

Any cluster-tilted algebra is the relation extension of a tilted algebra. Given the distribution of a cluster-tilting object in the Auslander–Reiten quiver of the cluster category, we present a method to construct all tilted algebras whose relation extension is the endomorphism ring of this cluster-tilting object.     

Variational analysis of fully coupled electro‐elastic frictional contact problems

We consider a mathematical model which describes the static frictional contact between a piezoelectric body and a foundation. The material behavior is described with a nonlinear electro‐elastic constitutive law. The novelty of the model consists in the fact that the foundation is assumed to be electrically conductive and both the frictional contact and the conductivity on the contact surface are described with subdifferential boundary conditions which involve a fully coupling between the mechanical and electrical variables. We derive a variational formulation of the problem which is in the form of a system coupling two hemivariational inequalities for the displacement and the electric potential fields, respectively. Then we prove the existence of a weak solution to the model and, under additional assumptions, its uniqueness. The proofs are based on recent results for inclusions of subdifferential type in Sobolev spaces (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Polymer Nano- and Microparticle Based Systems for Medical Diagnostics

Summary: Synthesis, properties and medical diagnostic applications of hydrophilic nano- and microspheres with carboxyl, aldehyde and hydroxyl groups on their surface are described. The particles were obtained by emulsion copolymerization of styrene, acrolein, methyl methacrylate, methacrylic acid, and 2-hydroxyethyl methacrylate carried on in water media and initiated with potassium persulfate. Stabilization of particles' suspensions was provided by addition of sodium dodecyl sulfate to polymerizing mixture or by formation of surfactants in situ in copolymerization involving acrolein or α-tert-butoxy-ω-vinylbenzyl-polyglycidol macromonomer (PGL). Relations between interfacial properties of these particles and their ability for covalent immobilization of proteins, with eliminated or at least reduced nonspecific adsorption of these species were investigated. The particles with covalently attached proteins (antigens or antibodies) were used for preparation of diagnostic tests based on visual or turbidimetric observation of particles' aggregation or by monitoring changes in their electrophoretic mobility accompanying specific antigen (or antibody) binding. The later test was directed toward determination of antibodies against Helicobacter pylori. Principle of a new type of diagnostic test based on photonic crystals of microspheres are described.     

A Nonsymmetric Correlation Inequality for Gaussian Measure

Letμbe a Gaussian measure (say, onRⁿ) and letK,LRⁿbe such thatKis convex,Lis a “layer” (i.e.,L={x: ax, ub} for somea, bRanduRⁿ), and the centers of mass (with respect toμ) ofKandLcoincide. Thenμ(K∩L)μ(K)·μ(L). This is motivated by the well-known “positive correlation conjecture” for symmetric sets and a related inequality of Sidak concerning confidence regions for means of multivariate normal distributions. The proof uses the estimateΦ(x)> 1−((8/π)^1/2/(3x+(x²+8)^1/2))e^−x2/2,x>−1, for the (standard) Gaussian cumulative distribution function, which is sharper than the classical inequality of Komatsu.     

An application of the Lefschetz fixed-point theorem to non-convex differential inclusions on manifolds

A selector theorem for non-convex orientor fields on closed manifolds is given and the Lefschetz fixed point theorem is used to establish an existence result for these ones.